docs: def new_multidigraph(self, name, data=None, **attr):
          """Return a new instance of type MultiDiGraph, initialized with the given
          data if provided.
  
          :arg name: a name for the graph
          :arg data: dictionary or NetworkX graph object providing initial state
  
          """
          self._init_graph(name, 'MultiDiGraph')
          mdg = MultiDiGraph(self, name, data, **attr)
          self._graph_objs[name] = mdg
          return mdg